On the track a sharp horse is anxious to get going and will often prance beside the out rider, or pony horse. He may even try to take a little nip at the pony and quickly pull his head away. This is a strong sign that the horse is ready to run a race.

As the pony breaks into a canter when the warm-up for the race starts the race horse will also break into a canter immediately.

Horses that are ready to run a race are more relaxed, yet have an alert look, tail raised and a healthy glow of their coat.

A dull horse will walk along with his head down and his tail between his legs. He does not look like a happy horse that is ready to run his best race. He may have his ears turned back rather that pricked and alert. He may show signs of resistence breaking into the gallop for the warm-up.. His eyes may be moving quickly and his nostrils may be flaring.
SOme will even grit their teeth and sweat so much until it turns into a white foam called washiness, and may even rear, or buck away from the handler.

Some horses can be a bit nervous in the paddock , or post parade and then settle down once the get to the starting gate. Some horses are very settled in the paddock and post parade, then get antsy once the load in the gate. And the gate can be a very dangerous for horse and rider. It is always good to look for a well schooled horse.

When the track is muddy look for horses that are lifting their legs high. This is a sign that they do not like a sloppy track.

These are all things I look for when I attend a race. My Dad's uncle was a trainer years ago, and he and my Dad were very close. So like it or not, I went to the track. These were always things that I was taught to look for. So from an early age, these are the things I always look for at the track. Good luck to you

ADD: For the troll that gave me a thumbs down, why don't you come out of hiding and give a better answer than mine. In fact, if you would grow up and quit following me around giving me thumbs down, just post a better answer. That's all.